Clinched seam construction and formation



Sept. 11, 1962 w. c. BROOKSON 3,053,409

CLINCHED SEAM CONSTRUCTION AND FORMATION Filed Aug. 2, 1960 IN V EN TOR.

W/Ll/4M (W/719i 8 BROOK-501V United States Patent Ofiice 3,053,409 Patented Sept. 11, 1962 3,053,409 CLINCHED SEAM CONSTRUQTIQN AND FQRMATKQN William Charles Broolrson, Hamilton, ()ntario, Canada,

assignor to American an Company, New York, N.Y.,

a corporation of New Jersey Filed Aug. 2, 1960. Ser. No. 46,913 6 Claims. (#Cl. Mil-67) The present invention relates to the clinching of can ends onto can bodies to facilitate the vacuumizing of double seamed cans prior to the final double seaming operation, and has particular reference to the formation of a clinched seam wherein conventional can body and end flanges are rolled together to interlock them in such manner as to positively prevent the lining compound which is carried on the end or cover flange, from seating on the body flange to hermetically seal oil the interior of the can.

In the canning of comminuted products such as powdered milk, ground coffee and the like, it is necessary to remove as much as possible of the air which is entrapped within the can and within the product contained therein prior to the final double seaming operation in order to prevent subsequent deterioration of the product by oxida tion. Removal of this air is usually effected by placing the filled but unsealed can in a closed chamber and subjecting the chamber to a high vacuum in order to evacuate the interior of the can.

In such vacuumizing operation, vacuums as high as 29.8 inches of mercury may be employed. Since auto matic equipment is usually employed, the time during which the evacuating process can be effected is necessarily limited and the vacuum is created in the vacuum chamber in a relatively short time. As a result, there is a definite tendency for the air within the can to be drawn from the can with great velocity, and the resultant outrush of air from the can, unless controlled, frequently carries with it a portion of the comminuted product.

Obviously, removal of the product from the can interior in such manner is very undesirable. In order to prevent it, the usual practice is to apply the can cover to the can body prior to the time the can is inserted into the vacuumizing chamber, and to provide for passageways in either the body or the cover through which the air may be withdrawn, these passageways being carefully dimensioned to limit and control the rate of withdrawal of the air.

A generally used method of providing such passageway is to secure the can cover to the can body in a preliminary seaming operation wherein the can body and end flanges are rolled together to form an incomplete, non-hermetic seam which is referred to as a clinched seam, this seaming operation being known as clinching operation. No particular difficulty is encountered in the formation of such seams when a low vacuum is being drawn, inasmuch as it is possible to use clinched seams which are quite loose and which provide relatively large passageways for the flow of air, since a loW vacuum does not pull the air from the can interior violently enough to carry the product with it. Such loosely clinched seams can be easily formed without danger of creating a hermetic seam through which the air cannot pass. However, when very high vacuums are being utilized, the clinched seam must be relatively tight in order to prevent the air from being pulled from the can too rapidly, and there is the ever present possibility that in tight seams the endlining compound will seat on the body flange and create a seal which is completely hermetic, or so close to being hermetic as to effectively prevent the desired withdrawal of the air from the container interior.

A relatively tight clinched seam is also advantageous for use with packing processes wherein the vacuum within the can is replaced by an inert gas such as carbon dioxide or nitrogen, while the can is still in the closed chamber, for in such processes it is a common practice to introduce the can into the outside atmosphere prior to the final seaming operation, and a tight clinched seam is necessary to prevent the inert gas from spilling out of the can and being replaced, in part at least, by the outside air during the transfer of the can from the vacuumizing and gassing chamber to the closing machine. The tighter the clinched seam, the less chance there is of such loss of inert gas.

The present invention provides a solution to this problem by providing a clinched seam construction which positively insures against seating of the end lining compound on the body flange to form a hermetic seal, and yet produces a seam which is tight enough to control the flow of air from the can when high vacuums are being used. This is effected by tightly rolling spaced portions of the seam together in such manner that the end lining compound carried by the cover in such spaced portions is pressed into engagement against the can body flange, thus locking the cover and can body together and holding them against untoward relative axial movement so that the seam does not open up to an undesirable extent when the can is subjected to external vacuum. However, the seam, between these tightly rolled portions, is formed with loosely rolled portions wherein the cover flange is lifted upwardly away from the body flange in order to positively eliminate the possibility of having the end lining compound in these portions seat upon the body flange. While in these loosely rolled areas there is metal-to-metal contact between the contiguous portions of the can cover and can body, such contact is discontinuous because of the inherent irregularities in the metal of these parts and is not effective in preventing the passage of the air through these portions of the seam.

The clinched seam of the instant invention is formed by a specially profiled, generally circular clinching roll which is provided with an endless clinching groove which is radially non-concentric with the clinching roll axis in order to create the alternate loose and tight seam portions, and which groove, axially of the roll is of wavy or sinuous configuration so that it is provided with a series of high spots which actually lift the cover flange upwardly away from the body flange in the loose seam portions. As a result of the fact that the cover flange is lifted away from the body in the loosely formed seam portions, there is substantially no chance of having the end lining compound in such areas seat on the body flange and passage of air through the seam is always insured.

An object of the invention therefore is the provision of a clinched seam construction wherein the seam is formed with alternately loosely and tightly rolled portions in such manner that the seating of the end lining compound in the loosely rolled portion is effectively prevented.

Another object of the invention is the provision of such a clinched seam which can be formed between conventional can bodies and ends, and which requires no special body or end configurations.

Yet another object is the provision of a tightly clinched seam which is effected to prevent the loss of gas from a clinched can after the gas filled clinched can is passed into the outside atmosphere preparatory to the final seaming operation.

Another object of the invention is the provision of a method of forming such a clinched seam.

Still another object is the provision of a specially constructed seaming roll for effecting the formation of such seams.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

FIGURE 1 is a side elevation of a can having its end or cover secured in place in a clinched seam made according to the principles of the instant invention, the view also showing in operative position relative to said can certain operating parts of a clinching machine, including a specially profiled clinching roll which is designed to form the said clinched seam;

FIG. 2 is a plan view of the clinched can and the clinching machine parts shown in FIG. 1;

FIG. 3 is a fragmentary vertical section on an enlarged scale taken through an upper peripheral portion of the can of FIGS. 1 and 2, but showing the can end in assembled position on the can body preparatory to the clinching operation;

FIG. 4 is a vertical section, on the same scale as FIG. 3, taken substantially along the line 44 in FIG. 2, this view being taken through the loosely formed portion of the clinched seam, the view also including, in dot and dash lines, a vertical section taken through the corresponding portion of the clinching roll which effects the formation of such loosely formed seam portion; and

FIG. 5 is a vertical section taken substantially along the line 55' in FIG. 2, this view being taken through a tightly rolled portion of the clinched seam and also showing in dot and dash lines a vertical section taken through the corresponding portion of the clinching roll which forms the tightly rolled seam portion.

As a preferred and exemplary embodiment of the instant invention the drawings illustrate a can of the conventional double seamed variety which comprises a tubular can body 12 preferably formed with a conventional side seam 14 and having its lower end closed by a recessed bottom end member 16 which is secured thereto in a conventional double seam 18. The can 10, after being filled with a suitable comminuted or powdery product such as powdered milk (not shown), has applied to its upper end a conventional end or cover member 20 of the type which is adapted to be sealed to the body 12 in a conventional double seam.

In order to permit the formation of such a double scam, the can body 12 is provided at its upper end with an outwardly extending annular flange 22 which normally projects from the can body 12 in a generally horizontal plane, as best seen in FIG. 3. The can end or cover member 20 is provided with a depressed center panel 24 which at its outer edge merges into an upwardly extending annular wall 26 which in the trade is referred to as a countersink wall. This countersink wall 26 in turn merges into an annular, outwardly extending cover flange 28 which at its outer edge is bent into a downwardly and inwardly extending curl 30. The underside of the cover flange 28 carries an end lining compound 32 which normally comprises a thin film of a rubbery material, which when compressed between the cover flange 28 and body flange 22 in the conventional finished double seam (not shown) provides a hermetic seal.

When the cover member 20 is initially placed in position in the upper end of the can body 12, as best seen in FIG. 3, the end lining compound 32 comes into loose contact with the upper surface of the body flange 22. With these parts thus positioned, the filled can is fed into a clinching machine wherein the formation of the clinched seam of the instant invention is effected. In such machine, the cover member 20 and can body 12 are clamped together under pressure between a seaming chuck 40, shaped to fit into the depressed cover member 20 and engage against the panel 24 and against the inner surface of the countersink wall 26, and a lifter pad 42 which fits into the recessed bottom end members 16.

After being thus clamped together, a clinching roll 44, made according to the principles of the instant invention, is moved radially of the can and brought into contact with the outer surface of the cover flange 28 and curl 26 in order to reshape the cover flange 28 and body flange 22 to form a clinched seam S, which firmly secures the cover member 20 in position on the can body 12, but which is not hermetically sealed and thus permits the passage of air from the interior of the can when the clinched can is subsequently introduced into a vacuumizing chamber (not shown).

The clinching roll 44 is carried by a shaft 46 and is mounted for axial rotation, being either positively driven by the shaft 46 or idly affixed thereto. Suitable means are provided to effect a relative circumferential movement of the rotating clinching roll 44 around the upper periphery of the can 10 and cover 20 to thereby effect formation of the clinched seam S. This may be done either by moving the clinching roll 44 bodily around the can it) and cover 20, or by rotating the can 10 and cover 20 on their own axes and maintaining a seaming roll shaft 46 in a fixed position relative thereto.

As best seen in FIG. 1, the clinching roll 44 is formed with an upper annular shoulder 48, which extends inw ardly over the cover flange 28, and a body portion 50 which is disposed immediately below said shoulder. An endless annular clinching groove 52 of special configuration is cut into an outer periphery of the body portion 50. This clinching groove 52 throughout its length is uniform in vertical cross-sectional contour as best seen in FIGS. 4 and 5, but is generally vertically sinuous or wavy as viewed in side elevation (see FIG. 1) and is formed with a plurality of evenly circumferentially spaced high portions 54 which are offset upwardly relative to the intervening low portions 56. The distance of offset is comparatively small, and may be in the nature of .025", although this figure may be varied somewhat on either side and still produce the desired results.

In addition to its serpentine configuration, the groove 52 is irregular in that it is not concentric with the axis of the seaming roll 44, but is preferably formed of a. plurality (here shown as three) of eccentric groove segments 58 each of which extends around the clinching roll 44, thus forming what in effect is a three lobed groove. The eccentricity of the segments 58 is, however, comparatively minor so that they merge smoothly into each other at their ends at points which are designated by the letter B, the groove 52 at such points being spaced its maximum distance from the axis of the clinching roll 44 (as best seen in FIG. 2). The total eccentricity of the segments 53 is not critical, but as an example, there may be radial variations of approximately .055 in the groove 52 of a roll wherein the diameter of the body portion 50 is approximately 1.977". As best seen in FIG. 1, the body portion 56 is not actually circular but has a circumferential contour which is substantially parallel to the contour of the clinching groove 52, being formed of three eccentric segments which merge smoothly into each other.

The clinching groove 52 is formed so that there is a definite relationship between its eccentricity and its sinuosity, the low spots 56 of the groove 52 coinciding with the points E of greatest radial spacing from the roll axis,

and the high spots 54 lying midway between the points E and coinciding with those portions of the groove 52 having the shortest radial spacing.

When the clinching roll 44 is moved inwardly against the flange 28 of the cover member 20, the clinching groove 52 reshapes this flange 28 to roll it downwardly and inwardly beneath the can body flange 22, and this movement of the cover flange 28 in turn bends the body flange 22 downwardly and inwardly, the result being that these flanges are rolled together and interlocked to form the clinched seam S of the instant invention.

Because of the unusual configuration the seaming groove 52, this clinched seam is not formed of uniform tightness, but rather comprises a series of loosely clinched portions, which will be hereinafter referred to by the letter L, and a series of tightly clinched portions which will hereinafter be referred to by the letter T, the portions L and T merging into each other smoothly and evenly, as best seen in FIG. 1.

At the tightly clinched portions T, the can body and end flanges 22, 28 are tightly rolled together in such manner that the end lining compound 32 seats upon the body flange 22 as clearly seen in FIG. 5, thus effecting a substantially hermetic seal at these portions.

The tight seam portions T are formed by the portions E of the clinching groove 52, because at such points the clinching groove 52 is spaced radially outwardly the greatest distance from the roll axis, and thus extends farthest towards the axis of the can body 12 and cover 20. Also, the portions E coincide with the low spots 56 of the groove 52 and the combination of these two factors effects the maximum reshaping of the can parts and in effect gives the tight seam portions T a contour which closely approximates that of a full first operation seam.

Laterally of the tight seam portions T, however, the cover flange 28 is gradually lifted upwardly awayfrom the body flange 22 by the high spots 54 of the clinching groove 52, and in addition, is rolled less tightly in a lateral direction as the portions 54 of the clinching groove 52 become operative. As a result, the lining compound 32 in such seam portions is positively lifted out of contact with the body flange 22, and is prevented from seating thereon. As seen in FIG. 4 the body flange 22 may be reshaped slightly, even in the loose seam portions L, but is nevertheless maintained out of contact with the lining compound 28 of the cover.

Thus, when the clinched can is placed in the vacuumizing chamber and subjected to external vacuum, the air within the can passes easily and readily through the loose seam portions L and the desired vacuum within the can is quickly obtained, despite the fact that met-al-to-rnetal contact between the can body and cover may be present in such loosely rolled portions.

It will be clear that the invention is not limited to a clinching roll wherein the lobes which form the tight seam 5 portions T are formed by eccentric segments in the manner shown, but that the lobes may be formed in any manner, as long as the groove contains portions of different radial spacing relative to the roll axis. It will also be clear that the invention is not limited to a three lobed clinching groove, but that a groove having one or more lobes will effect alternate loose and tight seam portions, the frequency and spacing between such portions however, being determined by the number of lobes used. In every construction, however, the low portions of the clinching groove will coincide with the groove lobes, so that these portions of the groove will product tight seam portions.

After the air has thus been removed from the can, it is necessary to dissipate the vacuum within the can in order to prevent its replacement by the external air if the clinched can is to be introduced into the outside atmosphere prior to the final seaming operation. In such event, the vacuum in the chamber is replaced by an inert gas such as nitrogen or carbon dioxide which is held at substantially atmospheric pressure. Because of the high vacuum within the can, such inert gas passes through the loose seam portions L and enters the can until it establishes a substantially atmospheric pressure therewithin. Thereafter, the clinched gassed can may be introduced into the external atmosphere, and then fed into a closing machine wherein the final double seam is formed in the conventional manner. Because of the fact that the gas pressure within is substantially in balance with the atmospheric pressure, and because the passageways in the loosely seam portions L are restricted by the metal-to-metal contact in such areas, there is substantially no tendency for the gas in the can to be replaced by the external air during the time the can is being transferred from the chamber to the closing machine, and thus the oxygen content of the finally seamed can is held to a minimum.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts and in the steps of the method described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. In a container adapted to be vacuumized or gassed prior to hermetic sealing thereof, the combination of a can body having an outwardly extending flange, a can end having an outwardly extending flange, and a ring of sealing material carried on the underside of said can end flange, said flanges being relatively tightly interlocked in one area and being relatively loosely interlocked in an adjacent area, said can end flange being vertically spaced from said can body flange in said loosely interlocked area to maintain said sealing material on said can end flange out of contact with said can body flange to prevent the formation of a hermetic seal in said loosely interlocked area.

2. In a container adapted to be vacuumized or gassed prior to hermetic sealing thereof, a can body having an outwardly projecting peripheral flange, a can end formed with an outwardly projecting peripheral flange, and a ring of sealing material carried by one of said flanges and disposed between said flanges, said flanges being tightly interlocked at spaced intervals to form tight seam portions and being loosely interlocked between said tight seam portions to form loose seam portions, said can end flange being vertically spaced from said can body flange in said loose seam portion to prevent the sealing material in said loose seam portions from creating a hermetic seal between said flanges.

3. In a container adapted to be vacuumized or gassed prior to hermetic sealing thereof, the combination of a can body formed with an outwardly projecting peripheral flange, and a can end formed with an outwardly projecting peripheral flange having a ring of sealing material on the underside thereof, said flanges being interlocked to form a non-hermetic clinched seam of axially sinuous configuration comprising gently merging alternate low and high interlocked flange portions, said sealing material being disposed in superposed vertically spaced relation to said body flange in said high portions of said clinched seam to prevent the formation of a seal between said flanges thereby permitting subsequent vacuumizing or gassing of said container.

4. The combination of claim 3 wherein said flanges are relatively loosely interlocked at said high portions of said sinuous seam and relatively tightly interlocked at said low portions of said sinuous seam.

5. In a container adapted to be vacuumized or gassed prior to hermetic sealing thereof, the combination of a can body having a cylindrical upper wall terminating in an outwardly extending flange, and a can end having an upstanding cylindrical countersink wall terminating in an outwardly extending flange with said countersink wall disposed within and adjacent to said can body upper wall,

a ring of sealing material carried by one of said flanges and disposed between said flanges, said flanges being tightly interlocked at spaced intervals to form tight searn por- 5 tions and being loosely interlocked between said tight seam portions to form loose seam portions, said can end flange being vertically spaced from said can body flange in said loose seam portions to prevent the sealing material in said loose seam portions from creating a hermetic seal 10 between said flanges.

References Cited in the file of this patent UNITED STATES PATENTS Hills June 24, 1930 Coyle Dec. 7, 1948 Ayres July 3, 1951 Lohuis Aug. 26, 1958 

